Preparation of kerosene type petroleum hydrocarbon solvents substantially free from objectionable odors



3,485,747 PREPARATIDN F KERQSENE TYPE PETROLEUM HYDROCARBON SOLVENTSSUBSTAN'HALLY FREE FRUM OBJECTIONABLE ODD-RS Joseph Phillips, Petrolia,Pa., assignor to Witco Chemical Company, Inc, New York, N.Y., acorporation of Delaware No Drawing. Filed July 14, 1967, Ser. No.653,325 Int. Cl. C10g 29/20 US. Cl. 208289 Claims ABSTRACT OF THEDISCLOSURE The preparation of kerosene type petroleum hydrocarbonsolvents from a starting petroleum hydrocarbon fraction which ischaracterized by markedly objectionable inherently present odors andsubstantially reducing said odors by a procedure which involvesadducting said starting fraction with urea whereby to form (1) an adductbetween the urea and hydrocarbons in said starting fraction, and (2) anon-adductible material, said non-adductible material containing theobjectionable odor-causing materials, and then recovering the kerosenetype petroleum hydrocarbon solvent, substantially free of objectionableodors, from the urea adduct.

This invention relates to a process for removing objectionable odorsfrom inherently malodorous petroleum hydrocarbon solvent fractions ofcertain types, hereafter described in detail.

While petroleum hydracarbon solvents are widely used in variousindustrial and commercial products, such solvents as, for instance,kerosene, even in a quite purified state, have a very pronounced odorwhich, for many purposes, is highly objectionable and undesirable.

Various procedures have been proposed, and utilized, to reduce oreliminate this pronounced odor, including extensive sulfonation,hydrogenation, chlorination, oxidation, and various chemical andphysical purification treatments. Such treatments, generally speaking,are relatively expensive and none has been adequately successful inproducing a fully satisfactory substantially odor-free petroleumhydrocarbon solvent such as kerosene. Sulfonation procedures, whilesubstantially changing the odor, produce a product which still has aquite intense odor of a somewhat sweet nature. Extensive hydrogenationproduces a product with a reduced odor level, but appreciableundesirable odor is nevertheless present and the treatment is relativelyexpensive. Chlorination, oxidation and other chemical and physicaltreatments generally produce only a slight improvement in the odor ofthe product.

It has been discovered, in accordance with the present invention, thatthe malodors of malodorous petroleum hydrocarbon solvent fractions,notably those characterized as kerosene or boiling in the kerosenerange, can be very substantially reduced and such fractions can beproduced in a form in which the malodors are markedly reduced bycontacting an inherently malodorous petroleum hydrocarbon solventfraction having a boiling point between 415 and 490 F. and an A.P.I.gravity between 44 and 50, and an odor panel rating of at least 3, withurea thereby to form a solid urea adduct in a liquid non-adductiblefraction, separating said solid adduct from the liquid non-adductiblematerial, washing the separated adduct to separate therefrom adheringnon-adductible material, breaking the adduct to provide saidsubstantially odorfree petroleum hydrocarbon solvent and urea, andrecovering said substantially odor-free petroleum hydrocarbon solvent.The urea adduct may easily be separated from the non-adducted fraction,as, for example, by filtration or the like, followed by washing, andthen the adnited States Patent 0 ice duct is broken or decomposed torelease the adducted fraction as, for example, by treatment with water,heating or the like, but especially (1) by heating to a tem perature ofabout 175190 F. in the presence of the deodoriZed petroleum hydrocarbonsolvent previously recovered in the process, or (2) by heating to saidtemperature under substantially anhydrous conditions.

The treatment with urea is effected by contacting the inherentlymalodorous petroleum hydrocarbon solvent fraction with urea as, forexample, at a temperature between 20 F. and 100 F. and preferably 60 F.to F. In general, the amount of urea is 20 to and preferably 40 to 60weight percent based on the hydrocarbon fraction. The contacting may beeffected in the presence of solvents, diluents or activators for theadduct formation as, for example, benzol, acetone, methyl ethyl ketone,methanol, petroleum ether, non-adductible fractions of material treated,etc. Amounts of solvent diluents ranging from about 0 to 500 andpreferably 0 to weight percent based on the fraction being treated, andamounts of activators, such as methanol, of 1 to 10 and preferably 2-3weight percent based on the urea, can be used. In accordance with aparticularly advantageous embodiment of the invention, in place of theconventional solvents, the contacting to form the urea adduct can beeffected in the presence of a non-adductible liquid fraction previouslyproduced in the process, in which case preferably from 50 to 150 weightpercent of this non-adductible fraction, based on the startingmalodorous hydrocarbon, is used. Since it is the nature of thediscovery, pursuant to the present invention, that the non-adductiblefraction of the starting malodorous petroleum hydrocarbon contains themalodorous material, and since the purpose of the process of the presentinvention is to obtain a petroleum hydrocarbon solvent fractionsubstantially free from malodorous materials from malodorous petroleumhydracarbon feed-stocks, it is further surprising, indeed, that theprocess is not interfered with by utilizing a non-adductible fraction,which contains the malodorous bearing materials, as the diluent for theadduction.

After the adduct is formed, the solid adducted fraction is separatedfrom the liquid non-adducted fraction by known procedures as, forexample, by filtration, settling, centrifugal separation or the like,and the solid adduct is washed. The adduct washing may be effected withthe organic solvents of various types as well as with an adductedfraction previously produced in the process. As a part of the overallprocess of the present invention, the adduct must be carefully washed inorder to remove the adhering non-adductible material. This is because,as has been discovered, the odoriferous constituents are present in thenon-adductible material and small portions of said malodorousconstituents cause substantial objectionable odor. In an illustrativecase, starting with a feed stock having an odor panel rating of 3.6, thehydrocarbon fraction recovered from the unwashed urea adduct cake, afterbreaking, had an odor panel rating of 3.2, after one washing had an odorpanel rating of 2.8, after two washings had an odor panel rating of 1.7,and after three washings had an odor panel rating of 1.4. In eachwashing, the volume of wash solvent was one-tenth of the volume of thestarting feed stock. After completion of the washing step, the ureaadduct is broken, as indicated above, whereby to provide the desiredsubstantially odor-free petroleum hydrocarbon solvent, and urea, andsaid substantially odorfree petroleum hydrocarbon solvent is thenrecovered. The treatment with urea, in accordance with the presentinvention, sometimes results in imparting a very slight urea ordor tothe recovered substantially odor-free petroleum hydrocarbon solvent. Tothe extent that this may be regarded as undesirable, it can readily beremoved by contacting said substantially odor-free petroleum hydrocarbonsolvent with a small proportion of activated bauxite, as by percolatingthrough a bed of said bauxite. It may be pointed out that activatedbauxite has no effect in removing odors of the type which areresponsible for the malodors in the starting inherently malodorouspetroleum hydrocarbon fractions with the removal of which malodors thepresent invention is concerned.

The evaluation of odors by panel rating has been developed for thetesting of Odor of Petroleum Wax (ASTM Method D 1833-61T). As adapted tothe rating of odor in petroleum hydrocarbon solvents, such as kerosene,it involves the selection of a panel consisting of at least five peoplewho are all qualified to detect varying odor intensities. This panelevaluates the odor intensity of a series of three to four samples at onetime. Each panel member sniffs each sample and gives it a numericalrating. Each sample is coded. The average of the numerical ratings bythe panel members is calculated and recorded as the Odor Panel Rating.Repeatability on the same sample tested by the panel on different daysis 0.3; and this does not require that the same members be on the panelboth times.

Rating description Rating No: Description of odor None. 1 Slight. 2Moderate.

3 Strong. 4 Very strong.

The odor panel rating of the starting inherently malodorous petroleumhydrocarbon fraction, as pointed out above, is at least 3 and, in thecase of an untreated hydrocarbon fraction, is commonly 3.5 or 4. Where astarting petroleum hydrocarbon fraction has undergone a certain refiningtreatment, for instance, acid refining, it will generally have asomewhat lower odor panel rating, for instance, 3, which is still highlyobjectionable for many purposes. The starting petroleum hydrocarbonfraction may be any petroleum hydrocarbon fraction of natural orsynthetic origin within the boiling point, viscosity and gravity rangesset forth above and having an odor panel rating of at least 3. Thus, forexample, the fractions may be obtained from Pennsylvania crudes,Mid-Continent crudes, Gulf Coast crudes, Middle Eastern crudes,Fischer-Tropsch products and the like.

The starting inherently malodorous petroleum hydrocarbon fractions whichare utilized in the practice of the process of. the present inventioncan be prepared by any one of various known procedures. Thus, forexample, kerosenes are commonly prepared, in the refining of crudepetroleum hydrocarbons such as Pennsylvania crude oils or Mid-Continentcrude oils, by taking 01f a fraction within certain boiling pointranges, kerosenes generally comprising mixtures predominately ofparaffinic hydrocarbons in the range of decanes to hexadecanes.

Such kerosenes conventionally have odor panel ratings of 3.5 to 4. Evenwhen subjected to known purification treatments of the characterreferred to above, such as sulfonation, hydrogenation, and chlorination,they are usually still characterized by odor panel ratings of 3 or more.

The specific chemical structure or nature of the malodorous constituentsinherently present in the starting malodorous petroleum hydrocarbonfraction is not known and has not been characterized. That it is notaldehydic or ketonic in character, nor of amine, sulfide or mercaptanstructure, would appear to follow from the fact that materials of suchcharacter form urea adducts (see, e.g. US. Patent No. 2,985,641 and thehereafter mentioned Brooks et al. article), nor is it of a charactersuch as is exemplified by acetonitrile or similar nitrile compounds suchas propionitrile or higher nitriles.

The following examples are given by way of illustration and not oflimitation:

Example 1 A petroleum distillate (hereafter called Solvent A) of thefollowing properties was treated:

API Gravity 46.0 Initial boiling point F 415 olT F "75 End point F 480To 1,000 ml. of Solvent A were added 300 g. urea and 10 ml. methanol.The mixture was stirred at room temperature. After 10 minutes, adductionoccurred as shown by a 15 F. temperature rise. After 30 minutesadditional stirring, the precipitated adduct was filtered through aBuchner funnel and washed with 3-100 ml. portions of a previouslyproduced adducted fraction. The adduct was decomposed with hot water F.)and the hydrocarbon layer liberated (48% by weight of the stock). Odorpanel ratings were as follows:

Odor panel rating Solvent A (untreated stock) 4 Solvent A (acid refinedstock) 3 Recovered solvent (adducted fraction) 2.5

Example 2 Example 1 was repeated except that the starting stock wasinitially diluted with an equal volume of a previously producednon-adductible fraction. Odor panel ratings were as follows:

Odor panel rating Solvent A (untreated stock) Solvent A (acid refinedstock) Recovered solvent (adducted fraction) 1.5 Non-adductible fraction4+ carbon fraction enriched in content of the desired type ofhydrocarbon. Such techniques have been known particularly for separatingstraight chain hydrocarbons from branched chain hydrocarbons. The ureaadducts generally form with the straight chained hydrocarbons, leavingthe branched hydrocarbons as a non-adducted fraction, thus allowing afractionation separation of the stragiht chain hydrocarbons from thebranched chain hydrocarbons. Such procedures are shown in numerouspatents and publications illustrative of which are US. Patents Nos.2,656,342; 2,666,048; 2,672,457; 2,673,195; and 2,731,- 455; the articleCrystalline Adducts of Urea with Linear Aliphatic Compounds, byZimmerschied et al., Ind. and Eng. Chem., Vol. 42, N0. 7, pp. l3001306(July, 1950); and Brooks et al. The Chemistry of Petroleum Hydrocarbons,Vol. I, Reinhold Publishing Co., New York. 1954, pp. 241-274. However,such prior patents and publications have nothing to do with and teachnothing whatsoever about removal of malodors from inherently malodorouspetroleum hydrocarbon fractions. Indeed, the nature of the odorsinherently present in certain petroleum hydrocarbons and the sensoryperception thereof are not entirely understood, and there is no known orrecognized relationship between properties of a petroleum hydrocarbonfraction which will form or will not form an adduct and the inherentodor of such a fraction. It is therefore entirely unexpected andsurprising that a urea adduct treatment of the specific inherentlymalodorous petroleum hydrocarbon fractions described above will yieldproducts having a substantially lower odor.

I claim:

1. A process for preparing a kerosene type petroleum hydrocarbon solventwhich is substantially free from objectionable odors from a malodorouspetroleum hydrocarbon fraction having a boiling point between 415 F. and490 F., an A.P.I. gravity between 44 and 50, and having an odor panelrating of at least 3, which comprises adducting said malodorouspetroleum hydrocarbon fraction with urea to form a mixture of a solidadduct fraction and a liquid non-adductible fraction, saidnon-adductible liquid fraction containing substantially all of theobjectionable malodorous material present in said malodorous petroleumhydrocarbon fraction, separating said solid adduct from saidnon-adductible liquid fraction, washing the separated solid adduct toremove therefrom adhering non-adductible material, breaking the adductto release the urea and recovering said petroleum hydrocarbon solventhaving an odor panel rating of not more than 2.5.

2. A process according to claim 1, in which said malodorous petroleumhydrocarbon fraction is an untreated stock having an odor panel ratingof 4.

3. A process according to claim 1, in which the adduction is carried outin a mixture containing a non-adductible liquid fraction which wasseparated from a previous urea adduction step involving said malodorouspetroleum hydrocarbon fraction having an odor panel rating of at least3.

4. A process according to claim 1, in which said malodorous petroleumhydrocarbon fraction is kerosene.

5. A process according to claim 4, in which said re covered kerosene iscontacted with activated bauxite.

References Cited UNITED STATES PATENTS 3,231,489 1/1966 Mahar 208-3082,221,301 11/1940 Kipper 208-289 2,834,716 5/1958 Champagnat et al. 2082,914,455 1/1959 Keller 208-25 3,163,632 12/1964 Leas et al. 208253,328,313 6/1967 Dellow 208-25 FOREIGN PATENTS 708,597 4/1965 Canada.1,408,798 7/1965 France.

215,199 10/ 1956 Australia.

DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant Examiner

